Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Jun 18 2023 01:16:45

AWUS01 KWNH 180116
FFGMPD
IAZ000-180415-

Mesoscale Precipitation Discussion 0516
NWS Weather Prediction Center College Park MD
916 PM EDT Sat Jun 17 2023

Areas affected...central Iowa

Concerning...Heavy rainfall...Flash flooding possible

Valid 180115Z - 180415Z

Summary...Scattered storms are producing heavy rainfall while
training just northwest of Des Moines.  Flash flooding is possible
this activity through 04Z.

Discussion...Persistent convection over the course of the
afternoon has organized into a focused band along an axis
extending from north of Ames to about 40 WSW Des Moines recently.
The band was oriented parallel to southwesterly flow aloft while
not propagating, allowing for training/repeating heavy rainfall
along that aforementioned axis.  The pre-convective airmass
(1000-1500 J/kg MLCAPE and 1.5 inch PW values) was supporting
efficient rain processes with the ongoing activity, while ascent
associated with a mid-level vorticity maximum near Sioux Falls was
also fostering updrafts.  Because the axis of convection was not
moving much over the past hour or so, MRMS-estimated rain rates
were beginning to peak in the 2-2.5 inch/hr range beneath the
heavier cores, which was approaching or locally exceeding 1.5-2.5
inch/hr FFG thresholds across the region.

The longevity of the developing flash flood risk is a bit
uncertain, but may last through at least 04Z.  CAMs suggest that
the ongoing complex will eventually pick up forward speed/eastward
propagation through the early overnight hours that would
dramatically lessen the flash flood threat by lessening rain
rates.  This process may take a few hours to unfold, however, with
flash flooding becoming more likely as long as storms stay along
their current axis.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!6bjqEH0DF1qf-36wg8mbv5PhzQ6jIAgJt9oZ91nb2O-gwR92ys8vGNnIISLt6Vz7hqhc=
yyobKftOSV9wbeSge298cNA$  for graphic product...

ATTN...WFO...ARX...DMX...DVN...OAX...

ATTN...RFC...MBRFC...NCRFC...NWC...

LAT...LON   43269309 43119224 42169225 41519268 40799358=20
            40739513 41459525 42629441 43109394=20

=3D =3D =3D
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